First, the variant:
Title payouts are figured by the following formula:
(TITLE MULTIPLIER x YOUR Superstar's Salary)
Note that this is opposed to receiving the payout of the title multiplier x your OPPONENT'S salary.
Reason for change:
This suggestion stems from what was actually a mistake in my first reading of the rule book, where for whatever reason I assumed that this was the rule.
As it stands with the correct rule, Superstar salaries are all negative--meaning, the higher your salary, the more negative it is. You have to pay your salary when you pass the Manager's square. You have to pay your salary to your opponent when you lose. And, with the correct rules, your opponent gains the title multiplier times your superstar's salary when you lose a title match--meaning that it's all bad for you, and completely beneficial to your opponent for you to have a higher salary.
All of this is fine, excepting the fact that not all superstars have "equitable" cost and salary levels. Take for example JBL and Undertaker--JBL is cheaper than UT in both cost to hire AND salary, and yet they both fight exactly the same--+5 in a match. As it stands, the only two reasons to hire more expensive superstars with the same stats is that either the more "efficient" stars have been hired already, or you just happen to be a fan of one particular Superstar.
This means that hiring the more efficient superstars is all positive with no negative. You pay out less for losing, and your opponent earns less for defeating them in title matches.
If you change the title defense rule to be YOUR superstar's salary x the belt's multiplier, this changes, at least a small bit. Now it is more profitable for you to defend the belt with a superstar with a higher salary. If you defend the World belt with someone with a $12,000 salary, your payout will be $60,000. However, if you defend your title with someone with a $15,000 salary, your payout will be $75,000! This means that your opponent can hire a lower salary guy and win the title, but he'll recieve less payout.
I'm not sure how the designers overlooked this, but this at least adds a nice bit of risk and reward that simply isn't present in the rules as printed--as it is, more salary = all negative. This grants those higher-priced superstars at least a bit of an advantage.
This has been tested and doesn't break anything--in fact, it makes the game much more interesting. It is still best in the long run to hire the more "efficient" superstars, but now those who have the higer salaried stars at least get a benefit--and one that can be quite significant in the short run. Note that the difference in defending with a higher salaried superstar can be enough extra profit alone just to pay that star's salary for a round!
I personally wouldn't recommend playing without this variant, actually. It improves the game a great deal and gives it a bit of balance I think is lacking in this area. Give it a try and let me know how it works for you.